Reviving this old thread, what was the long term outcome of these machined boxes?
The steering box in my 450SLC has quite bad play in the centre position. Its been re-sealed, and the coupling changed, but the play remains.
NB: the steering box internals on the 107 and 116 boxes are different, but the boxes do bolt up. the 107 has a different ratio and if a 116 box is fitted the car will have the turning radius of an ocean liner.